Field of the Invention
The present invention relates to an injection molding system. In particular, the present invention relates to a molding system in which an insert part is inserted into a mold of an injection molding machine to form a plastic molded article integral with the inserted insert part.
Description of the Related Art
There is a molding method in which an insert part is inserted into a mold of an injection molding machine, and a molten resin is injected into the inserted insert part to form a plastic molded article integral with the insert part. This is called insert molding and is performed to add value to the plastic molded article or achieve high functionality. In the plastic molding, a part of a metal or plastic material is used as the insert part to be inserted into the mold. A robot may be used to insert the insert part into the mold.
In some injection molding methods to control the quality of molded articles by determining the good/bad of the molded articles, the quality is determined by directly inspecting the molded articles. Alternatively, an injection molding machine for manufacturing molded articles may be configured to indirectly determine the quality by detecting the maximum value (peak pressure) of a resin pressure detected during a molding process or physical quantities, such as the screw's most advanced position (minimum cushion amount), speed, temperatures, and the like during the molding process. In some cases, moreover, the good/bad of molded articles may be determined by detecting physical quantities such as the weights and sizes of molded articles that are finished after completion of the molding process.
In an existing method for directly inspecting molded articles, the external appearances of the molded articles are inspected by human eyes or a sensor or the like. In a conventional method for detecting physical quantities, it is determined whether or not physical quantities such as a pressure, position, speed, and temperature are within their tolerances. Poor appearances of the molded articles include discoloration and burning of the molded articles, silver streaks, voids, weld lines, flow marks, bubbles, jetting, contamination, and the like. Although any of these methods are available, the method for directly inspecting molded articles generally requires much labor and cost for the inspection. Therefore, the indirect inspection based on physical quantities is performed in many cases.
Japanese Patent Application Laid-Open No. 2000-71303 discloses a technique in which the good/bad of a molded article is determined by measuring physical quantities during injection molding in plastic molding such that an insert part is inserted into a mold and a molten resin is injected into the inserted insert part to form the molded article.
Japanese Patent Application Laid-Open No. 2001-154717 discloses a technique in which a robot is mounted on an injection molding machine and used to insert an insert part into a mold of the injection molding machine.
Japanese Patent Application Laid-Open No. 61-114832 discloses a technique in which various variables, such as the cycle time, injection time, kneading time, peak injection pressure, switching pressure, and cushion amount, are detected and recorded in a molding cycle of an injection molding machine.
Japanese Patent Application Laid-Open No. 2013-86358 discloses a technique in which physical quantities that are considerably related to poor appearance are detected and displayed on a display device of an injection molding machine.
The so-called insert molding is disclosed in Japanese Patent Applications Laid-Open No. 2000-71303 and No. 2001-154717. Japanese Patent Application Laid-Open No. 2000-71303 also discloses how to detect the physical quantities during the injection molding for the determination of the good/bad. Further, Japanese Patent Applications Laid-Open No. 61-114832 and 2013-86358 disclose techniques in which the good/bad is determined by detecting the physical quantities during the molding process and physical quantities such as the weights and sizes of finished molded articles, in conventional injection molding, not insert molding. In any of these techniques, however, the good/bad is determined by using only the physical quantities related to finished molded articles and the physical quantities during the molding process, so that the cause of bad molded articles, including that of the insert part, may not be able to be investigated.